Transparent ultra-wideband electromagnetic shielding wave absorber for wireless and visible light communication integrated system

Abstract

The invention discloses a transparent ultra-wideband electromagnetic shielding wave-absorbing body for a wireless and visible light communication integrated system. The transparent ultra-wideband electromagnetic shielding wave-absorbing body is formed by arranging one or more metamaterial units, each metamaterial unit is formed by tightly attaching an upper ITO-PET-PDMS structure and a lower ITO-PET-PDMS structure; each ITO-PET-PDMS structure comprises a transparent substrate PDMS layer, a polyethylene glycol terephthalate (PET) layer and an ITO ceramic thin film layer from top to bottom, and the transparent substrate PDMS layer, the PET layer and the ITO ceramic thin film layer are sequentially arranged from top to bottom. The structure designed by the invention has the characteristics of broadband wave absorption, wide-angle wave absorption and optical transparency. The transparent ITO ceramic thin film is adopted to construct a multi-resonance topological structure, the wave absorption rate of the transparent ITO ceramic thin film exceeds 90% at 4.2-16.3 GHz (the relative bandwidth is 118.0%), the wave absorption rate of the transparent ITO ceramic thin film exceeds 75% within the incidence angle of 60 degrees, and the transparent ITO ceramic thin film can be applied to electromagnetic energy absorption covering a plurality of wireless communication frequency bands such as GPS and WiMAX. The structure designed by the invention has high optical transmittance.

Description

Technical Field

[0001] The present invention belongs to the technical field of artificial electromagnetic materials, and specifically relates to a transparent ultra-wideband electromagnetic shielding absorber material for electromagnetic compatibility applications of wireless and visible light communication integrated systems. It has the characteristics of optical transparency in the visible light band and ultra-wideband, wide-angle absorption and electromagnetic shielding in the microwave band, and can be applied to optical transparent covers, electromagnetic shielding, and electromagnetic compatibility. Background Art

[0002] With the development of 5G / 6G communication and optical communication theory and technology, more and more signal transceiver modules are integrated in mobile terminal devices such as mobile phones and tablets, and highly integrated systems with multiple modules of wireless communication and optical communication are receiving more and more attention. How to ensure the good operation of various modules across GPS, WiMAX, 5G / 6G millimeter wave frequency band wireless communication and visible light communication frequency band is a major problem that needs to be solved.

[0003] On the one hand, the electromagnetic energy leaked by wireless communication modules of different frequency bands during operation will interfere with the normal operation of other devices and affect human health, so electromagnetic shielding materials are needed; on the other hand, visible light communication is based on the reuse of lighting sources to achieve communication functions, which requires the device housing to have high light transmittance. Existing electromagnetic shielding methods such as metal shielding covers and coatings with electromagnetic shielding materials cannot meet the needs of visible light communication.

[0004] In recent years, artificial electromagnetic structural materials represented by metamaterials and metasurfaces have unique physical properties that natural materials do not have, and have received widespread attention in the fields of electromagnetic compatibility and electromagnetic shielding. For example, in 2019, researchers proposed a metamaterial absorber with wave-absorbing properties, which reduced the electromagnetic coupling between multiple antennas (IEEE Access, Vol. 7, pp. 57469-57475). Subsequently, researchers combined transparent conductive ceramic films such as indium tin oxides (ITO) and fluorine-doped tin oxide (FTO) with metamaterial structures to achieve optically transparent absorbers.

[0005] For wireless communication and visible light communication integrated system applications, the absorber is required to have ultra-wideband, wide-angle absorption and optical transparency. The present invention is based on artificial electromagnetic absorbing materials and ITO transparent conductive ceramic film, and through the Jerusalem type and four ring structures, realizes an optically transparent ultra-wideband, wide-angle electromagnetic absorber for electromagnetic shielding of wireless and visible light communication systems. Summary of the invention

[0006] This patent aims to propose a design method for a transparent ultra-wide bandwidth angle absorber for electromagnetic shielding applications in wireless and visible light communication systems, which has the characteristics of ultra-wideband, wide angle, optical transparency and compact structure. The absorber is composed of a Jerusalem type and four ring structures, and is obtained by closely fitting two ITO-PET-PDMS (polydimethylsiloxane) structures. It can be used for electromagnetic compatibility and electromagnetic shielding, and has broad application prospects.

[0007] The technical solution of the present invention is as follows:

[0008] A transparent ultra-wideband electromagnetic shielding absorber for wireless and visible light communication integrated systems, composed of a single or multiple metamaterial units;

[0009] Each metamaterial unit is made up of two ITO-PET-PDMS structures tightly bonded together; each ITO-PET-PDMS structure consists of three layers from top to bottom: transparent substrate PDMS (polydimethylsiloxane, Polydimethylsiloxane, PDMS)), polyethylene terephthalate (Polyethylene terephthalate, PET), and transparent ITO ceramic film. ITO is indium tin oxide (ITO).

[0010] Furthermore, an ITO ceramic film pattern is etched on the lower surface of the ITO-PET-PDMS structure located in the upper layer; the ITO ceramic film pattern consists of two parts: a Jerusalem-shaped structure located in the center and a square ring-shaped structure located around it.

[0011] Furthermore, the PDMS thickness of the ITO-PET-PDMS structure located in the upper layer is h1, the square resistance of the ITO ceramic film is Ω1, and Jerusalem type and four ring structure patterns are etched therein; adjusting the size of the PDMS thickness h1 can adjust the angular stability of the absorber, and adjusting the square resistance of the ITO ceramic film Ω1 and the size of the Jerusalem type and four ring structure patterns etched therein can adjust the absorbing bandwidth of the absorber.

[0012] Furthermore, the lower surface of the ITO-PET-PDMS structure located in the lower layer is completely covered with an ITO ceramic thin film layer.

[0013] Furthermore, the PDMS thickness of the ITO-PET-PDMS structure located in the lower layer is h2, and the square resistance of the ITO ceramic film is Ω2; adjusting the PDMS thickness h2 can adjust the absorptivity and absorbing bandwidth of the absorber, and adjusting the square resistance Ω2 of the ITO ceramic film can adjust the reflection and transmission characteristics of electromagnetic waves.

[0014] Furthermore, the upper and lower ITO-PET-PDMS structures are tightly bonded by OCA optical adhesive.

[0015] Furthermore, the number and arrangement of the metamaterial units contained in the absorber depends on the size of the applied device space and the electromagnetic shielding index, at least 1.

[0016] Furthermore, the thickness of the ITO ceramic film has little effect on the wave absorption characteristics and can be determined according to the process of the ITO ceramic film, such as the currently common thicknesses of 50nm, 175nm, 188nm, etc.

[0017] Furthermore, the square resistance of the ITO ceramic film affects the wave absorption and optical transmittance, and can be adjusted according to the requirements for electromagnetic shielding in the microwave band and visible light transmittance.

[0018] Furthermore, the transparent substrate PDMS can also be made of transparent materials such as polyvinyl chloride (PVC) and quartz glass.

[0019] Technical effects and advantages of the present invention:

[0020] 1. The structure designed by the present invention has the characteristics of broadband wave absorption, wide angle wave absorption and optical transparency. The transparent ITO ceramic film is used to construct a multi-resonance topological structure, and the wave absorption rate in 4.2-16.3GHz (relative bandwidth 118.0%) exceeds 90%, and the wave absorption rate within 60° incident angle exceeds 75%, which can be applied to electromagnetic energy absorption covering multiple wireless communication bands such as GPS and WiMAX.

[0021] 2. The structure designed by the present invention has high optical transmittance. It uses a transparent substrate and a transparent low-resistance ITO ceramic film, and the number of the overall substrate is 2 pieces and the number of ITO ceramic films is 2 layers. It has high optical transmittance and is suitable for visible light communication.

[0022] 3. The upper and lower ITO-PET-PDMS structures of the present invention are tightly attached by means of OCA optical adhesive (optically clear adhesive) and the like, and the overall structure is compact. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a three-dimensional schematic diagram of the absorber unit structure designed by the present invention;

[0024] Figure 2 It is a schematic diagram of the ITO ceramic film structure on the lower surface of the first block of the absorber unit structure designed in the present invention;

[0025] Figure 3 It is a schematic diagram of the lower surface of the second block material of the absorber unit structure designed in the present invention being fully covered with an ITO ceramic film;

[0026] Figure 4 is the reflection coefficient S of the absorber designed in the present invention when the electromagnetic wave is incident vertically 11 , transmission coefficient S 21 And the curve of absorption rate changing with frequency;

[0027] Figure 5 It is a curve showing the variation of the wave absorption rate of the wave absorber designed by the present invention with the frequency when the TE polarized electromagnetic wave is incident obliquely;

[0028] Figure 6 It is a curve of the wave absorption rate of the wave absorber designed by the present invention changing with frequency when the TM polarized electromagnetic wave is incident obliquely.

[0029] In the figure, 1a is the transparent substrate PDMS of the first ITO-PET-PDMS structure 1, 1b is the middle PET material of the ITO-PET-PDMS structure 1, and 1c is the ITO ceramic film etched on the lower surface; 2a is the transparent substrate PDMS of the second ITO-PET-PDMS structure 2, 2b is the middle PET material of the ITO-PET-PDMS structure 2, and 2c is the ITO ceramic film that fully covers the lower surface. DETAILED DESCRIPTION

[0030] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0031] The present invention is directed to wireless and visible light communication systems, and based on the metamaterial multi-resonance impedance matching theory and ITO ceramic thin film materials, achieves broadband, high-efficiency wave absorption at a large incident angle and optical transparency. In order to better illustrate the present invention, the following will be described in detail with reference to the accompanying drawings and specific implementation examples. The implementation examples described are exemplary and are intended to be used to explain the present invention, but are not intended to limit the present invention.

[0032] Embodiment 1

[0033] Depend on Figure 1The figure shows a three-dimensional schematic diagram of the absorber unit structure, which consists of two parts: from top to bottom, the first ITO-PET-PDMS structure 1 and the second ITO-PET-PDMS structure 2. From top to bottom, the ITO-PET-PDMS structure 1 is a transparent substrate PDMS1a with a thickness of h1 = 4.8 mm, a PET material 1b, and an ITO ceramic film 1c with an etched resistance of Ω1. From top to bottom, the substrate 2 is a transparent substrate PDMS2a with a thickness of h2 = 4.0 mm, a PET material 2b, and an ITO ceramic film 2c with a resistance of Ω1 of the full covering material. The unit period size p = 15 mm.

[0034] Figure 2 It is the ITO ceramic film pattern 1a etched on the lower surface of the first ITO-PET-PDMS structure 1 of the absorber unit structure. Pattern 1a consists of a Jerusalem-shaped structure located in the center and a square ring-shaped structure located around it. The structural parameters are: l1=10.0mm, w1=1.0mm, l2=13.0mm, a=5.0mm, b=4.0mm, and square resistance Ω1=30Ω / sq. The square resistance size and PDMS thickness h1 are adjusted to adjust the overall transmittance and equivalent impedance of the structure.

[0035] Figure 3 The lower surface of the second ITO-PET-PDMS structure 2 of the absorber unit structure is completely covered with an ITO ceramic film layer 2c, and the square resistance Ω2 = 10Ω / sq. The square resistance and the PDMS thickness h2 are adjusted to adjust the transmittance and resonance frequency of the entire structure.

[0036] The relative dielectric constant of the PDMS materials 1a and 2a is 2.75, and the loss tangent is 0.012.

[0037] The structure designed by the present invention is simulated using electromagnetic simulation software CST, and the reflection coefficient S of the metamaterial absorber at a vertical incident angle is 11 , transmission coefficient S 21 The curve of wave absorption rate changing with frequency is as follows Figure 4 As shown, the absorption rate is given by the reflection coefficient S 11 and the transmission coefficient S 21 According to the definition A=1-|S 11 | 2 -|S 21 | 2 It can be seen from the figure that within 4.2-16.3 GHz (relative bandwidth 118.0%), the absorption rate is above 90%. Among them, three resonant frequencies are generated, namely 5.6 GHz, 8.9 GHz and 15.4 GHz.

[0038] The absorption rates of the metamaterial absorber under TE polarization and TM polarization and different incident angles are as follows: Figure 5 and Figure 6 It can be seen that within the incident angle (θ) of 60°, within the range of 4.2 to 16.3 GHz (relative bandwidth 150.4%), the absorption rate of TE and TM polarizations is above 75%.

[0039] The solution provided in this embodiment can be expanded to other frequency bands by changing the relative dielectric constant, thickness, spatial spacing, and metamaterial unit structure parameters of the flexible transparent substrate, so as to meet the application requirements of wave absorption in a specific frequency band.

[0040] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A transparent ultra-wideband electromagnetic shielding absorber for wireless and visible light communication integrated systems, characterized in that: It is composed of a single or multiple metamaterial units; Each metamaterial unit is composed of two tightly bonded upper and lower ITO-PET-PDMS structures; each ITO-PET-PDMS structure consists of three layers from top to bottom: transparent substrate PDMS, polyethylene terephthalate, and ITO ceramic film.

2. The transparent ultra-wideband electromagnetic shielding absorber for wireless and visible light communication integrated system according to claim 1, characterized in that: An ITO ceramic film pattern is etched on the lower surface of the ITO-PET-PDMS structure located in the upper layer; the ITO ceramic film pattern consists of a Jerusalem-shaped structure located in the center and a square ring-shaped structure located around it.

3. The transparent ultra-wideband electromagnetic shielding absorber for wireless and visible light communication integrated system according to claim 2, characterized in that: The PDMS thickness of the ITO-PET-PDMS structure located in the upper layer is h1, the square resistance of the ITO ceramic film is Ω1, and Jerusalem type and four ring structure patterns are etched therein; adjusting the size of the PDMS thickness h1 can adjust the angular stability of the absorber, and adjusting the square resistance of the ITO ceramic film Ω1 and the size of the Jerusalem type and four ring structure patterns etched therein can adjust the absorbing bandwidth of the absorber.

4. The transparent ultra-wideband electromagnetic shielding absorber for wireless and visible light communication integrated system according to claim 1, characterized in that: The lower surface of the ITO-PET-PDMS structure located in the lower layer is completely covered with an ITO ceramic film layer.

5. The transparent ultra-wideband electromagnetic shielding absorber for wireless and visible light communication integrated system according to claim 4, characterized in that: The PDMS thickness of the ITO-PET-PDMS structure located in the lower layer is h2, and the square resistance of the ITO ceramic film is Ω2; adjusting the PDMS thickness h2 can adjust the absorptivity and absorbing bandwidth of the absorber, and adjusting the square resistance Ω2 of the ITO ceramic film can adjust the reflection and transmission characteristics of electromagnetic waves.

6. The transparent ultra-wideband electromagnetic shielding absorber for wireless and visible light communication integrated system according to claim 1, characterized in that: The upper and lower ITO-PET-PDMS structures are tightly bonded by OCA optical glue.

7. The transparent ultra-wideband electromagnetic shielding absorber for wireless and visible light communication integrated system according to claim 1, characterized in that: The number and arrangement of the metamaterial units contained in the absorber depends on the size of the device space and the electromagnetic shielding index, at least 1.

8. The transparent ultra-wideband electromagnetic shielding absorber for wireless and visible light communication integrated system according to claim 1, characterized in that: The thickness of the ITO ceramic film has little effect on the wave absorption characteristics and can be determined according to the process of the ITO ceramic film.

9. The transparent ultra-wideband electromagnetic shielding absorber for wireless and visible light communication integrated system according to claim 1, characterized in that: The square resistance of ITO ceramic film affects the wave absorption and optical transmittance, and can be adjusted according to the requirements of electromagnetic shielding in the microwave band and visible light transmittance.

10. The transparent ultra-wideband electromagnetic shielding absorber for wireless and visible light communication integrated system according to claim 1, characterized in that: Transparent substrate PDMS can also be made of transparent materials such as polyvinyl chloride and quartz glass.

Images